Why does the smell of a lighted instant stick spread to the entire room quickly?

Answer 1

its because of the phenomena known as diffusion, diffusion is the process in which the molecules move from the region of higher concentration to the region of lower conc. so when the stick is burnt the smell diffuses to the region of lower conc. as fast as possible.

Answer 2

The smell of a lighted incense stick quickly spreads throughout a room due to the volatile compounds in the incense that quickly vaporize at room temperature. This allows the scent to diffuse through the air molecules, reaching all corners of the room rapidly. The smoke produced by the burning incense also aids in dispersing the fragrance.